1. Field of the Invention
This invention relates to the sterilization of medical devices. In particular, this invention relates to systems, methods and devices for sterilizing lumens.
2. Description of the Related Art
Articles such as medical instruments are normally sterilized before use. There are many methods of sterilizing medical equipment, including heat treatment and chemical methods. Heat sterilization is normally performed with steam. Some equipment cannot withstand either the heat or the moisture from steam treatment. As a result, chemical sterilization is now commonly used.
Chemical sterilization uses a sterilizing fluid such as hydrogen peroxide, ethylene oxide, chlorine dioxide, peracetic acid, formaldehyde, or a combination thereof. A plasma may be induced to enhance the sterilization process. Although chemical sterilization is normally highly effective, it may not be as effective with medical devices having long, narrow tubes, or lumens. It is difficult for the sterilizing agent to completely penetrate and sterilize these long narrow tubes. In order to enhance the penetration of the sterilizing agent down the entire length of the lumen, several methods and several forms of apparatus have been developed to flow sterilizing agent through the length of the lumen, enhancing the effectiveness of the sterilizing treatment.
For example, U.S. Pat. Nos. 4,410,492 and 4,337,223 describe an apparatus and a method for sterilizing lumens in which the lumen is placed in a socket connected to a circulating pump. The pump circulates the sterilizing gas through the lumen. Although the method is effective in sterilizing the lumen, the commercial apparatus uses ethylene oxide as a sterilant, and sterilization requires times of about 2–3 hours. Ethylene oxide is toxic. Additional aeration time is needed to remove the residual.
U.S. Pat. No. 5,580,530 describes a method for delivering sterilizing agent through long, narrow lumens. The lumen is inserted into an adaptor connected to a vessel containing hydrogen peroxide. The vessel is called a booster. The lumen, adaptor, and booster are placed in a sterilization chamber. When the sterilization chamber is evacuated during the sterilization procedure, the hydrogen peroxide in the booster vaporizes and passes through the lumen, sterilizing the interior of the lumen.
An apparatus and a method for delivering sterilizing agent directly into long, narrow lumens is described in U.S. Pat. Nos. 4,943,414, 5,580,530 and 5,733,503. The lumen is inserted into an adaptor connected to a small vessel containing hydrogen peroxide. The adaptor and the vessel which contains the hydrogen peroxide are called the booster. The lumen, vessel, and adaptor are placed into a sterilization chamber. When the sterilization chamber is evacuated, the hydrogen peroxide vaporizes and passes through the lumen, providing the necessary hydrogen peroxide to the interior of the lumen. Although effective, the method has some disadvantages. First, in some forms of the apparatus, the booster must be “activated” manually by piercing a septum to make the hydrogen peroxide liquid accessible. Second, the booster is used only once before it is discarded. Third, the product has a limited shelf life. The storage and shipping conditions may affect the shelf life of the product.
In each of these sterilization methods, the lumen is held by a connecting device, a socket in the case of U.S. Pat. Nos. 4,410,492 and 4,337,223 or a truncated cone adaptor when using the method of U.S. Pat. No. 5,580,530. In all of these methods, there are areas of contact between the device and the lumen in the area where the lumen attaches to the connecting device. It is difficult for the sterilizing agent to penetrate into these contact areas. There is a need for an apparatus and a method of enhancing the penetration of sterilizing gas or vapor into these contact areas more effectively to allay any potential concerns about incomplete sterilization.
There are also contact areas between the parts of medical devices having two or more pieces. It is difficult to sterilize the contact areas between the parts which make up the medical device. There is a need for a method and an apparatus for enhancing the penetration of sterilant into the contact areas between the pieces which make up the medical device.
There is also a need for a method of sterilizing lumens which does not require the use of a booster with limited shelf life. Further, there is a need for a method which utilizes an apparatus which is reusable, to reduce costs.